Can't use Devonthink Services in Mac Mail.app on Catalina

Ah, thank you, that makes sense! My expectations were off. I can select all and “Take Rich Note”, but it excludes the email header information that would be important for record keeping. I can create a Forwarded message and then select all, but that creates some additional formatting.

Is there a better way to do this? Is this what Devon Mail Plug-ins used to do?